JP4825587B2 - Lid material having pressure valve function and container using the same - Google Patents

Description

  The present invention relates to a lid member for sealing an opening of a container that accommodates an object and a container using the same, and in particular, a pressure valve function that discharges gas in a container to the outside of the container when the internal pressure of the container increases. The present invention relates to a lid member provided and a container using the same.

  Sealing performance may be required for a container that contains an object and a lid that closes the opening of the container. For example, in the case of containing food, sealing is often required from the viewpoint of storage stability.

  On the other hand, when a sealed container containing moisture such as food is heated with a microwave oven or the like, the moisture contained in the object becomes water vapor, which increases the internal pressure of the container. In this case, if the internal pressure exceeds the strength of the container or the lid, the ruptured and heated contents may be scattered.

  For this reason, when heating a container that contains and contains an object containing moisture, it is necessary to open the container by partially peeling the lid material before heating, but this is a cumbersome operation and the user It is supposed to impair the convenience.

  In addition, there is also a lid material that cuts off a part of the lid material and closes it with a seal etc. to maintain the sealing performance, and peels off the seal due to an increase in internal pressure due to heating to discharge the gas in the container. If this is the case, there is no loss of user convenience. However, it is necessary to affix a sticker to an existing laminate, which increases the manufacturing process and the associated cost.

As a prior art aiming at solving such a problem, there is a “lid material and soft package” disclosed in Patent Document 1. In the invention disclosed in Patent Document 1, the sealant layer breaks due to an increase in internal pressure due to gas generation, and gas is discharged from between the sealant layer and the polyolefin resin (or polyolefin-related copolymer) layer provided immediately above the sealant layer. To do.
JP 2002-104474 A

The invention disclosed in Patent Document 1 reduces the strength of the sealant layer by heating, breaks it by internal pressure, and causes interfacial peeling from the polyolefin resin layer directly above.
In such a configuration, it is difficult to stably discharge the water vapor in the container. For example, as soon as the temperature of the lid becomes high and the softening of the sealant layer starts, there is a possibility that water vapor in the container may be blown out of the container all at once.

  An object of this invention is to provide the cover material provided with the pressure valve function provided with the stable degassing property, and the container using the same at low cost.

  In order to achieve the above object, the present invention provides, as a first aspect, a lid material that is heat-sealed at the peripheral edge of an opening of a container body to close the opening, and includes a surface layer, a polyolefin, and a cyclic olefin copolymer. A laminate having a polyester film layer laminated in contact with a mixed resin layer blended at a predetermined ratio, and a sealant layer positioned at the bottom, and the interface between the polyester film layer and the mixed resin layer is a release surface Provided with a cover material having a pressure valve function, characterized in that at least one back half cut cut from the sealant layer side is provided in a region which is constituted by a body and is inside the opening It is. In the above configuration, the polyester film layer is preferably formed of a PET film.

  In order to achieve the above object, the present invention provides, as a second aspect, a container wherein the opening is heat-sealed by the lid material according to any one of the first aspect of the present invention. It is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the lid | cover material provided with the pressure valve function provided with the stable degassing property, and the container using this can be provided at low cost.

[Composition of laminated structure material]
FIG. 1A shows the structure of a laminated structure material used as a lid material in the present invention.
The lid material is configured using a laminated material in which a surface layer 1, a polyester film layer 2, a mixed resin layer 3, an intermediate layer 4, and a sealant layer 5 are laminated in order from the surface layer side (outside of the container). In the following description, the direction that is the outer side of the container is defined as the upper side, and the direction that is the inner side of the container is defined as the lower side. In addition, although the same effect is acquired even if it is the layer structure which replaced the polyester-type film layer 2 and the mixed resin layer 3 as shown in FIG.1 (b), the following description is shown in FIG.1 (a). Perform based on layer structure. Regardless of which of the polyester film layer 2 and the mixed resin layer 3 is on the upper side, an adhesive layer 6 is provided on the opposite side of the mixed resin layer 3 from the polyester film layer 2 as necessary.

As the surface layer 1, polypropylene resin, polyamide resin, polyester resin, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride, polycarbonate or other plastic film or sheet, aluminum, iron, copper, and the main components thereof A metal foil such as an alloy or a metal plate, cellophane, paper, woven fabric, non-woven fabric, or the like can be used, and these may be laminated by selecting a single layer, or one or more. In consideration of dimensional stability, heat resistance, mechanical strength, printing suitability, etc., it is preferable to use polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), or nylon (Ny).
In addition, when using in order to seal the opening part of the container heated with a microwave oven, the surface layer 1 needs to be comprised only with a nonmetallic material.

As the polyester film layer 2, a known polyester film can be used, but it is preferable to use a PET film as a material. The polyester film layer 2 preferably has a surface wetting tension of 3.5 × 10 ⁻² N / m (35 dyn / cm) or more and 6.0 × 10 ⁻² N / m (60 dyn / cm) or less. It is particularly desirable that the wetting tension is 4.0 × 10 ⁻² N / m (40 dyn / cm) or more and 5.0 × 10 ⁻² N / m (50 dyn / cm) or less. The reason for this is that if the surface wetting tension is less than 3.5 N / m, the adhesive strength is reduced, and if it exceeds 6.0 N / m, the adhesive strength is improved. This is because it becomes difficult to adjust the peel strength.
In addition, the interface peeling strength with the mixed resin layer 3 can be adjusted by performing the surface treatment (for example, corona treatment) which changes surface roughness to the side used as the interface with the mixed resin layer 3 as needed.

  The mixed resin layer 3 is a resin that is poured between the surface layer 1, the polyester film layer 2, and the intermediate layer 4 when extruded and sand laminated. The thickness of the mixed resin layer 3 is preferably 10 μm to 30 μm in order to obtain a stable peel property.

In the present embodiment, the mixed resin layer 3 is a resin in which a cyclic olefin copolymer (COC) is mixed with polyolefin at a predetermined ratio. Examples of the polyolefin include polyethylene resin and polypropylene resin, but it is preferable to use low density polyethylene (LDPE). Here, COC is a preparation of a catalyst such as a so-called Ziegler catalyst or metallocene catalyst in a hydrocarbon solvent such as hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, and α-olefin and cyclic olefin. As such a copolymer, there is a trade name “Apel” manufactured by Mitsui Chemicals. As LDPE, there is a trade name “Suntec” manufactured by Asahi Kasei Chemicals Corporation.
The MFR (Melt Flow Rate) of the polyolefin is preferably 1 to 50 [g / min], more preferably 1 to 10 [g / min]. The density of the polyolefin is preferably 0.89 to 0.940 [g / cm ³ ]. The MFR of the cyclic olefin copolymer (COC) is preferably 1 to 40 [g / min], more preferably 5 to 25 [g / min].

  The mixed resin layer 3 can control the interfacial peel strength with the polyester film layer 2 by changing the mixing ratio of the low density polyethylene (LDPE) and the cyclic olefin copolymer (COC). It is possible to adjust.

  The content of the cyclic olefin copolymer (COC) is preferably 1 to 24% by weight, particularly preferably 5 to 20% by weight. This is because when the content is less than 1%, the interfacial peel strength becomes strong, and when it is more than 24%, the peel strength cannot be controlled.

  The intermediate layer 4 is a layer provided for the purpose of improving the strength of the lid member, and aluminum foil, PET, PE, paper, or the like can be used as a single layer or multiple layers. Note that the intermediate layer 4 may not be provided as long as the lid 50 can have a desired strength without the intermediate layer 4. In addition, when using in order to seal the opening part of the container heated with a microwave oven, the intermediate | middle layer 4 needs to be comprised only with a nonmetallic material.

  The sealant layer 5 is a layer for bonding (heat-sealing) the lid material to the container body, and the same material as the conventional lid material can be applied. The type of sealant material is selected according to the lowermost layer material of the intermediate layer 4 and the material of the container body 90.

The adhesive layer 6 includes polyethylene (PE), polypropylene (PP) low density polyethylene (LDPE), linear low density polyethylene (LLDPE), unstretched polypropylene (CPP), EMAA (ethylene-methacrylic acid copolymer resin), and the like. This is a layer for firmly peeling the mixed resin layer 3 and the adhesive layer 6 to prevent peeling between unintended layers. In addition, as a material, in order to ensure the adhesive strength with the resin for extrusion sand lamination which is a raw material of the mixed resin layer 3, the thing of the same system as resin used for extrusion sand lamination is good. Specifically, when mixing a cyclic olefin copolymer and a polyethylene resin as an extrusion sand laminating resin, a polyethylene resin is used. When mixing a cyclic olefin copolymer and a polypropylene resin as an extrusion sand laminating resin, polypropylene is used. It is recommended to use a resin. Further, in addition to the above, the role of the adhesive layer 6 is to reduce the longitudinal tearing property of the cyclic olefin copolymer contained in the mixed resin layer 3 and prevent longitudinal tearing when peeling from the mixed resin layer 3. Have a role.
The adhesive layer 6 may be a film-like one laminated with the surface layer 1 (or the intermediate layer 4) (wet laminate, non-solvent laminate, dry laminate, extrusion laminate, etc.), or the intermediate layer 4 by a method such as extrusion. You may form in one surface of (or surface layer 1). When using a film-like material, LDPE, LLDPE, CPP, EMAA, PET (an anchor coating treatment is applied to the mixed resin layer 3 side), or the like can be applied. In the case of an extruded resin, LDPE, LLDPE, PP, EMAA, etc. can be applied. If the uppermost layer of the intermediate layer 4 (or the lowermost layer of the surface layer 1) is formed of these materials and the layer itself has a function as an adhesive layer, the adhesive layer 6 is substantially unnecessary. Become.

Next, the back half cut formed in the laminated structure material will be described. Ideally, the back half-cut should be cut so that it reaches at least the mixed resin layer 3. However, in consideration of the accuracy of the half-cut, it can be applied appropriately according to the original fabric so that the function as a lid does not deteriorate. It ’s fine.
As shown in FIG. 1A, when the polyester film layer 2 is on the upper side, the back half cut 30 is provided from the sealant layer 5 that is the lowermost layer and reaches at least the mixed resin layer 3. However, the back half-cut 30 may reach the substantially central portion of the polyester film layer 2.
As shown in FIG. 1B, when the mixed resin layer 3 is on the upper side, the back half-cut 30 is provided from the sealant layer 5 that is the lowermost layer and reaches at least the mixed resin layer 3. The back half-cut 30 can be formed by a known method using a rotary die cutter, Heidel, laser, or the like.

  Hereinafter, a preferred embodiment of the present invention using the laminated structure material shown in FIG.

A lid member having a pressure valve function suitably implementing the present invention will be described.
FIG. 2 shows the structure of the laminated structure 100 that is the material of the lid member 50 in this embodiment. In the present embodiment, the cover material is formed using a laminated structure material having a surface layer 1 having a two-layer structure. The thickness of each layer shown in FIG. 2 is an example of the configuration and is not limited to this value.
The surface layer 1 has a structure in which a PET layer 11 and a nylon layer 12 are laminated in this order from the top layer. The PET layer 11 is a layer for printing a pattern or a pattern and for improving the strength of the surface layer 1. The nylon layer 12 is a layer provided to improve the mechanical strength of the surface layer 1.
The polyester film layer 2 is made of a PET film, and the surface roughness of the surface in contact with the mixed resin layer 3 is adjusted to a desired roughness by corona treatment as necessary.
The mixed resin layer 3 is formed using LDPE and a cyclic olefin copolymer as raw materials, and the ratio thereof is 85% for LDPE and 15% for the cyclic olefin copolymer.
The intermediate layer 4 is formed using a PET film.

A method for manufacturing the laminated structure 100 will be described.
First, a PET film to be the PET layer 11, a nylon film to be the nylon layer 12, and a PET film to be the polyester film layer 2 are dry-laminated. Also, a PET film to be the intermediate layer 4, a sealant film to be the sealant layer 5, and a PE film to be the adhesive layer 6 are dry-laminated.
Thereafter, while a mixed resin of LDPE and cyclic olefin copolymer (LDPE 85% + cyclic olefin copolymer 15%) is extruded between the polyester film layer 2 and the intermediate layer 4, these are sand-laminated to complete the laminated structure 100. .

  Hereinafter, the lid member according to the present embodiment will be described in detail on the assumption that the laminated structure 100 having the above configuration is used as a material.

  FIG. 3 shows a lid 50 for a food container according to this embodiment. FIG. 4 shows a container body 90 whose opening is sealed by the lid member 50. The periphery of the lid member 50 is heat sealed to the container body 90. An opening tab 50 q is provided on the peripheral edge of the lid member 50. Further, a back half cut 30 is formed in a region that is inside the container opening. The position where the back half-cut 30 is provided is arbitrary as long as it is inside the container opening, but is preferably provided near the center of the opening in consideration of stress concentration due to expansion of the lid material. In addition, although the straight back halfcut 30 is shown in FIG. 3, arbitrary shapes, such as V shape and a semicircle shape, may be sufficient. Moreover, it does not necessarily need to be continuous, and may be formed intermittently (in other words, in the form of a perforation).

  Since the laminated structure 100 is formed of only a non-metallic material, if the container body 90 is also formed of a non-metallic material, it can be used in a microwave oven.

It is assumed that the container body 90 contains an object containing moisture.
When the container main body 90 is heated, the moisture contained in the contents changes to water vapor, the internal pressure of the container rises, and the entire lid member 50 expands as shown in FIG.

  When the internal pressure of the container further increases, the gas in the container enters the back half-cut 30 as shown in FIG. Then, as shown in FIG. 7, the gas that has entered the back half-cut 30 causes interface peeling between the polyester film layer 2 and the mixed resin layer 3, and only the surface layer 1 and the polyester film layer 2 expand. The expansion of the mixed resin layer 3, the intermediate layer 4, and the sealant layer 5 stops.

  As shown in FIG. 8, the gas that has entered between the polyester film layer 2 and the mixed resin layer 3 advances these interface separations to the ring seal portion (the flange portion of the container body 90).

  When the interfacial separation between the polyester film layer 2 and the mixed resin layer 3 reaches the ring seal portion, stress concentration occurs in the ring seal portion, and the polyester film layer is located at any position of the ring seal portion as shown in FIG. 2 and the mixed resin layer 3 are peeled off. As a result, the gas in the container is discharged out of the container through the gap between the polyester film layer 2 and the mixed resin layer 3.

  Thus, the lid according to the present embodiment can perform smooth gas venting without performing any special operation before heating. Moreover, the interfacial peel strength between the polyester film layer 2 and the mixed resin layer 3 can be adjusted to such an extent that it gradually peels off due to the stress of the invading gas, and there is no risk that the gas in the container will be ejected all at once. Stable degassing.

Although the case where the internal pressure of the container increases due to the moisture contained in the contents becoming water vapor upon heating is described here as an example, stable degassing is possible even when the internal pressure of the container increases due to other reasons. It goes without saying that is possible.
For example, when sealing fermented foods or when sealing foods containing liquids in which carbon dioxide is dissolved, it is clear that the gas is released when the internal pressure becomes higher than a predetermined pressure due to the gas generated in the container. It is.

The said embodiment is an example of suitable implementation of this invention, and this invention is not limited to these.
For example, in the above embodiment, a configuration in which a container-like container and a lid member are combined is taken as an example. However, the contents may be sealed in a bag shape using a laminated structure different from the lid member.
Moreover, the process of laminating | stacking the laminated structure used as a cover material is not limited to the example shown in the said embodiment.
Further, the laminated structure itself as a base of the lid may be folded back, the sealant layers may be sealed, and the contents may be sealed in a bag shape.
As described above, the present invention can be variously modified.

It is a figure which shows the layer structure of the laminated structure used as the raw material of the cover material concerning this invention. It is a figure which shows the layer structure of the laminated structure used as the material of the cover material concerning suitable embodiment of this invention. It is a figure which shows the structure of the cover material concerning suitable embodiment of this invention. It is a figure which shows the structure of the container using the cover material concerning suitable embodiment of this invention. It is a figure which shows the state which the whole cover material expanded by heating. It is a figure which shows the state which the vapor | steam penetrated into the back half cut. It is a figure which shows the state which only the surface layer and the polyester-type film layer expanded with the vapor | steam which penetrate | invaded back half cut. It is a figure which shows the state which the interface peeling of the polyester-type film layer and the mixed resin layer advanced to the ring seal part. It is a figure which shows the state by which interface peeling of the polyester-type film layer and mixed resin layer produced in the ring seal part, and the vapor | steam in a container was discharged | emitted out of the container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface layer 2 Polyester-type film layer 3 Mixed resin layer 4 Intermediate layer 5 Sealant layer 6 Adhesive layer 11 PET film 12 Nylon film 30 Back half cut 50 Lid 50q Opening tab 90 Container body

Claims (3)

A lid that is heat-sealed at the peripheral edge of the opening of the container body and closes the opening,
A surface layer, a polyester film layer laminated in contact with a mixed resin layer in which a polyolefin and a cyclic olefin copolymer are blended at a predetermined ratio, and a sealant layer positioned at the bottom, the polyester film layer, It is composed of a laminate in which the interface with the mixed resin layer becomes a release surface,
A lid member having a pressure valve function, characterized in that at least one back half cut cut from the sealant layer side is provided in a region inside the opening.   The lid material having a pressure valve function according to claim 1, wherein the polyester film layer is formed of a PET film.   A container having an opening heat-sealed by the lid according to claim 1.

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